code: def add(self, item, priority):
      self.elements[self._ptr] = item
      tree_idx = self._ptr + self.capacity - 1
      self.update(tree_idx, priority)
      self._ptr = (self._ptr + 1) % self.capacity
      self._min = min(self._min, priority)
  
file_path: PARL/benchmark/fluid/Prioritized_DQN/proportional_per.py
imports: import numpy
label_desc: Use image node_id 3 for calling the SumTree obj's underlying member method code with example usage: obj.add(item, priority) without return types